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某0Cr12Mn5Ni4Mo3Al不锈钢自锁螺母在服役过程中出现开裂。对开裂螺母进行了宏观和微观断口形貌观察、表面能谱分析、显微组织及力学性能分析与测试等。结果表明:该螺母开裂原因为应力腐蚀开裂(SCC)。裂纹起源于法兰面与螺母体交接处,螺母体与法兰面呈直角此处易积液,螺母表面处理方式为钝化和涂MoS2,其耐蚀能较差。在腐蚀性潮湿大气环境中,干湿交替作用下螺母产生局部腐蚀点,在腐蚀点处萌生裂纹,裂纹在螺母圆周切向拉应力作用下扩展直至螺母开裂。 相似文献
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针对翼缘厚度80~120 mm重型热轧H型钢的开发,采用有限元模拟技术,对其变形过程进行了分析,研究了翼缘变形渗透情况。结果表明,翼缘厚度80~120 mm重型热轧H型钢变形后,距其翼缘内侧30%ti处存在最小等效塑性应变区,即该部位变形渗透效果最差;成品翼缘厚大于100 mm时,翼缘心部与翼缘外侧总等效塑性应变均值之差约为0.10,变形渗透程度不良,在成品道次开轧前,将翼缘表面温度降至900 ℃左右,其变形渗透程度得到显著改善;成品翼缘厚小于100 mm时,随着中间坯翼缘厚度由95 mm减小至80 mm,其变形渗透良好,变形更加均匀。 相似文献
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不锈钢平焊法兰与不锈钢管件的固定运用TIG焊接技术,实行法兰密封面自熔焊接,法兰非密封面加丝焊接,以实现法兰连接功能。 相似文献
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随着航空、航天制造技术的飞速发展,复杂精密构件的应用越来越广泛。在复杂精密构件或大厚度工件水浸式超声C扫描检测中,常常需要采用分区聚焦技术,针对不同厚度范围的检测区域,采用合适的参数进行扫描检测。研制的四通道水浸式超声C扫描检测系统及软件CScanPro,实现了一次扫描四个通道同时成像的分区聚焦检测功能,提高了检测效率,实用性强,软件运行稳定,界面友好。CScanPro软件也可应用于非聚焦四通道超声C扫描检测,已在3台超声C扫描检测系统中安装和使用,实际检测结果准确,满足测试要求。 相似文献
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铝合金法兰辗制工艺是通过连续局部塑性变形的积累使法兰整体壁厚减小、直径扩大、截面轮廓成形,最终使环件毛坯成为一定形状尺寸的法兰零件。法兰件辗制过程中,局部变形区存在厚度减小、周向伸长、轴向宽展的塑性变形,这种塑性变形的发生、发展和积累规律决定了法兰辗制变形和成形是渐变的,极大地减少了法兰开裂的倾向。本文通过对铝合金法兰辗制工艺的关键技术进行研究,成功实现批量生产。 相似文献
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0 IntroductionSteelconstructionisthebeststructureformagainstearthquakeforitsgoodmechanicalpropertiesandadaptability.Recentlydamagestosteelstructureonearthquakeshavebeenfrequentlyreported.BrittlefracturewasfoundonearthquakesofNorthridgeandHyogokenNanbu,… 相似文献
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Heng-Sheng Lin Chih-Wei Tung 《International Journal of Machine Tools and Manufacture》2007,47(14):2133-2139
Hole flanging with cold extrusion can avoid necking or fracture as encountered in conventional sheet metal-forming operations. Substantial flange height and lip thickness can be achieved with flange extrusion because the forming load is compressive. Using a hydraulic press, flange extrusions of 5 and 10 mm inner diameters were produced in pieces of cup-shaped galvanized steel, as well as aluminum 5052 workpieces with a thickness of 0.8 mm, both of which had a pre-hole on the cup bottom. As the punch load was exerted on the cup rim, a clamping force was applied to suppress dilation on the cup bottom.The experiments showed that with sufficient clamping force, significant flange height could be extruded. The utmost extruded flange of 5 mm i.d. was 6 times larger than that drawn from the conventional method, whereas that of 10 mm i.d. was 3.8 times larger than that drawn from the conventional method. However, no flange was extruded and buckling occurred on the cup bottom when the clamping force was insufficient. The experiments confirmed the results predicted by the FE simulation. For a selected flange inner diameter, the ratio of the extruded flange height to the increase in cup bottom thickness was directly related to the normalized clamping pressure, i.e. the ratio of clamping pressure to workpiece yield strength. Therefore, both the application of a larger clamping force or the use of low-strength workpiece materials facilitated the extrusion of flange while suppressing the dilation of the cup bottom. Flange extrusions with a larger diameter correspond to a smaller extrusion ratio or reduction of area. Experiments showed that a significant flange height could be extruded with a 10 mm inner diameter for both galvanized-steel and aluminum 5052, while results for extrusions with a 5 mm inner diameter were unfavorable when using galvanized-steel. High-strength materials and a high extrusion ratio required greater clamping force for the flange extrusion process, and consequently caused excessive forming load on the forming dies as well as on the hydraulic press, thus rendering the process less effective. 相似文献